Many aspects of reticulum cell sarcomas type B in BALB/c mice are being studied including differences between tumors in the amount of local as compared to general growth, differences in involvement of spleen, liver and nodes and differences in the capacity to form ascites. A pyrex glass helix has been developed which allows for greater normal or tumor cell replication per surface area. These helices can be implanted into the appropriate host providing a sensitive technique to isolate transformed neoplastic cells in the presence of a larger number of normal cells.